can b12 injections make you feel worse How Quickly Does a Shot Work? Benefits & What to Expect Feeling worse after B12 Injection:

Common side effects include: Injection site reactions mild pain, redness, swelling, or bruising at the injection site, typically resolving within a few days Headache usually transient and manageable with standard analgesia Nausea or dizziness particularly in the initial treatment phase Skin reactions including itching, mild rash, or acneiform eruptions Temporary urine discolouration red or orange urine is harmless and expected Diarrhoea or flushing usually mild and self-limiting In patients with severe megaloblastic anaemia, low potassium levels (hypokalaemia) may occur during initial intensive treatment, but this is uncommon in routine maintenance therapy

It is recognized for its stability and high resistance to enzymatic degradation, making it a valuable compound for controlled laboratory investigation

A Phase IIa trial published by Heffernan et al

Patients with pernicious anemia should be informed that they will require monthly injections of vitamin B12 for the remainder of their lives